The present invention relates to a semiconductor device and, more particularly, to a microwave transistor.
A low-noise transistor having a pattern as shown in FIG. 4 is conventionally widely used as a low-noise amplifying element for microwaves in the C to Ku bands. This pattern has a gate finger 12a, gate electrode pads 12, a source electrode pad 14, and a drain electrode pad 13. The gate finger 12a is straightly arranged on a pellet 11. The gate electrode pads 12 are led out from portions midway along the gate finger 12a to one side. The source electrode pad 14 surrounds the gate electrode pads 12. The drain electrode pad 13 is arranged on the other side of the source electrode pad 14 through the gate finger 12a. This pattern is called the .pi. type pattern. Bonding wires 16 are connected to the respective electrode pads 12, 13, and 14 through bonding balls 17.
In contrast to the .pi. type pattern, a low-noise transistor which forms a pattern by using aerial wirings has been developed in recent years. As shown in FIG. 5, this pattern has, e.g., a gate electrode pad 22, four gate fingers 22a, an H-shaped source electrode pad 24 and a source electrode path 24b, a source finger 24a, a drain electrode pad 23, two drain fingers 23a, and aerial wirings 25. The gate electrode pad 22 is arranged on a pellet 21. The four gate fingers 22a are led out from the gate electrode pad 22 to be parallel to each other. The source electrode pad 24 and the source electrode path 24b are arranged to sandwich the gate electrode pad 22 and the gate fingers 22a. The source finger 24a is led out from the source electrode path 24b and is arranged in a region sandwiched between the two central gate fingers 22a. The drain electrode pad 23 is arranged on the other side of the gate electrode pad 22 through the source electrode path 24b. The two drain fingers 23a are arranged in the two remaining regions sandwiched between the gate fingers 22a. The aerial wirings 25 connect the drain fingers 23a to lie across the source electrode path 24b. This pattern is called the H type pattern. Bonding wires 26 are connected to the respective electrode pads 22, 23, and 24 through bonding balls 27.
In the .pi. type pattern shown in FIG. 4, the gate electrode pads 12 are surrounded by the source electrode pad 14. In the H type pattern shown in FIG. 5, both the gate electrode pad 22 and the drain electrode pad 23 are sandwiched by the source electrode pad 24. Therefore, the area of the gate electrode pads or gate electrode pad 22 and the area of the drain electrode pad 23 are limited by the source electrode pads 14 and 24. More specifically, within the pellets 11 and 21 having a limited size, it is impossible to form the gate electrode pads 12 and 22 and the drain electrode pad 23 to have a large size, and a defect tends to be caused by misalignment in bonding.